JP5769023B2 - Method for producing silicon single crystal film - Google Patents

Description

  The present invention relates to a thinned and self-supporting silicon single crystal film and a method for manufacturing the same.

  In recent years, there is an increasing demand for reducing the thickness of a semiconductor substrate constituting various semiconductor devices such as solar cells by reducing the thickness thereof. In particular, in a solar cell, there is an advantage that the use of a semiconductor material necessary for manufacturing the semiconductor layer is reduced while the weight is reduced by thinning the semiconductor layer. In addition, by devising the solar cell structure, it becomes possible to increase the conversion efficiency of light-electricity, and there are many advantages for thinning in various aspects. In addition, the semiconductor substrate can be made flexible by thinning the film, and assembling of various devices can be simplified and the benefits in use can be improved.

  In the case of a conventional bulk silicon wafer, thinning by mechanical grinding or polishing has a limit in handling (handling), and a new thinning method has been proposed. As an example, a silicon wafer having an SOI (silicon on insulator) structure has attracted attention.

  As a method for manufacturing a wafer having an SOI structure, a bonding method, a SIMOX (separation by imprinted oxygen) method, and the like are known. In recent years, as an SOI wafer having a thin SOI layer, it is also called an ion implantation separation method (Smart Cut (registered trademark) method), which is one of bonding methods, from the viewpoint of obtaining an SOI layer in a wide range of film thicknesses. ) Has been proposed (see Patent Documents 1 and 2).

  In this ion implantation separation method, an oxide film is formed on the surface of the silicon wafer, and at least one of hydrogen ions or rare gas ions is implanted from the upper surface of the silicon wafer, and a microbubble layer (encapsulation layer) is formed inside the silicon wafer. Form. Next, the surface into which ions are implanted is bonded to the base substrate through an oxide film. Thereafter, heat treatment (peeling heat treatment) is applied to make the microbubble layer into a cleavage plane, and the silicon wafer is peeled off in a thin film shape on the base substrate side. Furthermore, a heat treatment (bonding heat treatment) is applied, and the peeled thin film silicon film is firmly bonded onto a base substrate bonded through an oxide film to form an SOI wafer.

  However, in such an ion implantation delamination method, it is necessary to apply heat at about 1000 ° C. when a silicon wafer is exfoliated into a thin film with a microbubble layer as a cleavage plane by applying a heat treatment (separation heat treatment). Therefore, the base substrate to be bonded to the surface of the silicon wafer on which ions are implanted is limited to a material having high heat resistance (can withstand heating at about 1000 ° C.) such as another silicon wafer or a glass substrate. There were restrictions on material selection.

  Furthermore, since the silicon film obtained by the ion implantation separation method is formed by peeling from the microbubble layer at the cleavage plane, it is difficult to control the film thickness. For this reason, even when the silicon film formed on the base substrate is polished for further thinning, it has been difficult to achieve uniform thinning.

  In the ion implantation separation method, since a silicon film is formed on the base substrate, such a silicon film is inferior in its self-supporting property and deformability and is difficult to handle in a subsequent process.

  As described above, in the silicon film obtained by the ion implantation delamination method, it has been extremely difficult to simultaneously achieve thinning, flexibility and large area.

JP-A-5-211128 Japanese Patent Laid-Open No. 10-321548

  The present invention has been made in view of such circumstances, and provides a thinned self-supporting silicon single crystal film, and a new heat treatment temperature at the time of peeling can be remarkably reduced. An object is to provide a method for forming a silicon single crystal film.

The gist of the present invention aimed at solving such problems is as follows.
[1] The Si content is 90 atomic% or more,
The thickness is 50 μm or less,
Self-supporting silicon single crystal film.

[2] The silicon single crystal film according to [1], wherein the area is 0.1 to 1000 cm ² .

[3] A silicon single crystal laminate formed by laminating the silicon single crystal film according to [1] and a heat resistant resin film.

[4] A step (1) of forming a halogen-containing silicon layer on a single crystal silicon wafer;
A step (2) of forming a high-purity silicon single crystal film having a desired thickness on the surface of the halogen-containing silicon layer;
Forming a heat-resistant resin film on the high-purity silicon single crystal film (3);
And a step (4) of peeling the high-purity silicon single crystal film together with the heat-resistant resin film with the halogen-containing silicon layer by heating.

[5] The method for producing a silicon single crystal film according to [4], wherein the steps (1) and (2) are performed by an epitaxial growth method.

[6] The method for producing a silicon single crystal film according to [4] or [5], wherein the steps (1) and (2) are performed by a plasma CVD method.

[7] The method for producing a silicon single crystal film according to any one of [4] to [6], wherein the heat-resistant resin film is made of a polyimide resin.

[8] The method for producing a silicon single crystal film according to any one of [4] to [7], wherein in the step (4), the heating temperature is 200 to 700 ° C.

1A to 1F are cross-sectional views showing the main parts of the manufacturing process of a silicon single crystal film.

  Hereinafter, the present invention will be described in more detail with reference to the drawings based on the following embodiments.

<Silicon single crystal film>
The silicon single crystal film 6 according to the present embodiment contains Si as a main component. Specifically, the silicon single crystal film according to the present embodiment contains 90 atomic% or more, preferably 97 atomic% or more of Si atoms.

  Moreover, the silicon single crystal film 6 according to the present embodiment may contain 10 atom% or less of halogen atoms as components other than Si. The halogen atom content is preferably as low as possible, and particularly preferably 3 atomic percent or less.

  The thickness of the silicon single crystal film 6 according to this embodiment is 50 μm or less, and preferably 10 μm or less. The lower limit of the thickness is not particularly limited, but is preferably 0.5 μm or more from the viewpoint of film strength and uniformity.

The silicon single crystal film 6 according to the present embodiment is self-supporting. The self-supporting property in the present invention means a self-supporting property that can maintain the form even when laminated with a flexible resin film.
The silicon single crystal film 6 according to the present embodiment is a thin self-supporting single crystal film, is excellent in flexibility, and can improve the benefits in use.

The area of the silicon single crystal film 6 according to the present embodiment is preferably 0.1 to 1000 cm ² . The silicon single crystal film 6 of the present invention is obtained by the method described later, has a large area, has a smooth surface, and has high thickness uniformity. The silicon single crystal film of the present invention having such a large area and excellent self-supporting property and flexibility can be used for a wide range of applications.

<Silicon single crystal laminate>
The silicon single crystal laminate according to this embodiment is a laminate formed by laminating the silicon single crystal film 6 and the heat resistant resin film 5.

  The heat-resistant resin film 5 is preferably a thermosetting resin having no softening point or a resin having a softening point of 200 ° C. or higher. Specifically, a thermosetting resin such as a polyimide resin can be used. In the present embodiment, a polyimide resin is preferable.

  The thickness of the heat resistant resin film 5 is not particularly limited, but is preferably 1 to 700 μm in this embodiment.

  In addition, when using a silicon single crystal laminated body as devices, such as for solar cells, the laminated body may contain the metal film. The metal film may be disposed between the silicon single crystal film 6 and the heat resistant resin film 5 or may be disposed on the silicon single crystal film 6 on the side not in contact with the heat resistant resin film 5. However, it may be arranged in both of them.

  Examples of the metal constituting the metal film include Cr, Al, and Ag. In the present embodiment, Ag is preferable.

  Although the thickness of a metal film is not specifically limited, In this embodiment, Preferably it is 0.01-700 micrometers. By setting it as this range, when peeling, the metal thin film on the film can be peeled without cracks, which is favorable.

  The metal film to be laminated may be processed into a shape such as an electrode in a subsequent process.

  The method for forming the metal film is not particularly limited, and the metal can be formed on the silicon single crystal film 6 of the present invention by a method such as vapor deposition, sputtering, or coating.

  The silicon single crystal film / metal film laminate of the present invention is used for manufacturing various semiconductor devices such as solar cells.

<Method for producing silicon single crystal film>
Next, a method for manufacturing the silicon single crystal film 6 according to this embodiment will be described.

Process (1)
First, a halogen-containing silicon layer 3 is formed on a single crystal silicon wafer 1 that serves as a substrate.

  The single crystal silicon wafer 1 used as the substrate is not particularly limited, but a silicon wafer having a mirror surface processed on the front and back surfaces and a thickness of about 100 to 700 μm is preferably used.

The area of the single crystal silicon wafer 1 is preferably 0.1 to 1000 cm ² , more preferably 1 to ²⁰⁰ cm ² . The area of the silicon single crystal film 6 is substantially equal to the area of the single crystal silicon wafer 1 that becomes the substrate.

  In the present embodiment, the halogen-containing silicon layer 3 is formed by an epitaxial growth method. As a method for performing epitaxial growth, plasma CVD, thermal CVD, vapor deposition, laser ablation, molecular beam epitaxy, pulsed laser deposition, or sputtering can be used.

  In this embodiment, it is preferable to use a plasma CVD method. The plasma CVD method (Chemical Vapor Deposition) is a method in which a reaction gas as a raw material is put into a plasma state, active radicals and ions are generated, a chemical reaction is performed in an active environment, and a film is deposited on a substrate. It is.

As the source gas (reaction gas), a mixed gas of a halogenated silane gas such as SiF ₄ , SiH ₂ F ₂ , SiCl ₄ , SiHCl ₃ , SiH ₂ Cl ₂ and hydrogen gas can be used. As the carrier gas, for example, He, Ar, and a mixture thereof can be used.

  In the present embodiment, a mixed gas of halogenated silane and hydrogen is preferably used. Plasma is generated in hydrogen gas and halogenated silane gas, and formation of the halogen-containing silicon layer 3 is started by epitaxial growth.

  Since the halogen-containing silicon layer 3 grows while incorporating halogen atoms into the structure of the silicon layer during epitaxial growth, the halogen-containing silicon layer 3 has a fragile structure as compared to the high-purity silicon single crystal film 4 described later. Therefore, it is considered that when the high-purity silicon single crystal film 4 is peeled off, the halogen-containing silicon layer 3 becomes a fracture surface, and the halogen-containing silicon layer 3 is broken to peel the silicon single crystal film 6.

  The concentration ratio between the halogenated silane gas and the hydrogen gas in the raw material gas is 1: 100 to 10: 100, more preferably 2: 100 to 8: 100. By setting this range, the single crystal silicon film 4 with good crystallinity can be formed. When the concentration ratio is smaller than this, etching becomes dominant and the film formation is remarkably slowed. If it is large, the crystallinity is disturbed, which is not preferable.

The pressure in the reaction vessel varies depending on the method of epitaxial growth, but is preferably 10 ⁻⁵ Pa to 10 Pa. More preferably, it is preferably 10 ⁻³ to 10 ⁻¹ Pa.

  The reaction temperature is 30 to 800 ° C. Preferably it is 100 to 600 degreeC. Within the reaction temperature range, the single crystal silicon film 4 having high crystallinity is obtained. Below 30 ° C., the halogen-containing silicon layer 3 does not adhere to the silicon wafer 1 and the halogen-containing silicon layer 3 cannot be formed. At 800 ° C., halogen atoms are not sufficiently taken into the silicon layer during epitaxial growth, and the desired halogen-containing silicon layer 3 is not formed. Therefore, the single crystal silicon film 6 tends not to peel off.

  The thickness of the halogen-containing silicon layer 3 can be changed as necessary. In the present embodiment, it is preferably 0.05 to 3 μm. By setting this range, the high-purity silicon single crystal film 4 can be satisfactorily formed and can be easily peeled off. If the halogen-containing silicon layer 3 is too thin, peeling tends to be difficult, and if it is too thick, the high-purity silicon single crystal film 4 tends not to be formed well.

  The halogen content of the halogen-containing silicon layer 3 is preferably 0.05 to 10 atom% or less, more preferably 0.1 to 3 atom% or less. By controlling within this range, the high purity silicon single crystal film 4 can be favorably and easily peeled off. Note that if the halogen content of the halogen-containing silicon layer 3 is too low, peeling tends to be difficult, and if it is too high, the high-purity silicon single crystal film 4 tends not to be formed well.

  In this embodiment, prior to the formation of the halogen-containing silicon layer 3, the surface treatment (step (0)) is performed to adjust the concentration of hydrogen gas to remove the oxide film 2 on the single crystal silicon wafer 1 serving as the substrate. ))It can be performed.

In the step (0), the reaction gas may be 100% hydrogen gas, or SiCl ₄ or SiF ₄ gas diluted with a rare gas such as He or Ar. By doing so, the oxide film 2 adhering to the surface of the single crystal silicon wafer 1 as shown in FIG. 1A can be removed as shown in FIG. Furthermore, halogen can remain on the single crystal silicon wafer 1, which is suitable for obtaining the single crystal silicon thin film of the present invention.

  The surface treatment (step (0)) of the single crystal silicon wafer 1 is appropriately selected according to the state of the single crystal silicon wafer 1. Alternatively, a single crystal silicon wafer 1 that has been surface-treated as shown in FIG.

Process (2)
Next, a high-purity silicon single crystal film 4 is formed on the halogen-containing silicon layer 3.

  In the present embodiment, the high-purity silicon single crystal film 4 is formed by epitaxial growth as in the step (1). As a method for performing epitaxial growth, plasma CVD, thermal CVD, vapor deposition, laser ablation, molecular beam epitaxy, pulsed laser deposition, or sputtering can be used. In the present embodiment, the plasma CVD method is preferable.

As the source gas, a mixed gas of silane gas and hydrogen gas such as SiF ₄ , SiCl ₄ , SiHCl ₃ , SiH ₂ Cl ₂ , SiH ₂ F ₂ , SiH ₄ , Si ₂ H _6, or the like can be preferably used.

  The concentration ratio of silane gas and hydrogen gas in the raw material gas is 0.5: 100 to 10: 100, more preferably 1: 100 to 5: 100.

  The reaction temperature is 30 to 800 ° C. More preferably, it is 100 degreeC-600 degreeC. By setting it within this range, a high-purity single crystal silicon film 4 with good crystallinity can be formed.

  The high-purity silicon single crystal film 4 contains 99 atomic% or more, preferably 99.9 atomic% or more of Si.

  The thickness of the high-purity silicon single crystal film 4 can be appropriately changed as necessary by controlling the reaction time, and is preferably 50 μm or less, more preferably 10 μm or less in the present embodiment. is there.

  The lower limit of the thickness is not particularly limited, but is preferably 0.5 μm or more from the viewpoint of film strength and uniformity. If it becomes thinner than this, it becomes difficult to peel the high-purity silicon single crystal film 4 satisfactorily from the single crystal silicon wafer 1 side, which is the substrate, in the peeling step (4) described later.

Step (3)
Next, a heat resistant resin film 5 is formed on the high purity silicon single crystal film 4.
The formation method is not particularly limited as long as the high-purity silicon single crystal film 4 and the heat-resistant resin film 5 are in close contact with each other. For example, a heat-resistant resin film may be formed on the high-purity silicon single crystal film 4 by a spin coat method or the like, or may be bonded to a heat-resistant resin film already formed into a sheet shape.

  The heat-resistant resin film 5 is excellent in flexibility and adhesiveness with the high-purity silicon single crystal film 4, and is made of a heat-resistant resin that shrinks by heating in a peeling step (4) described later.

  As the heat-resistant resin, a thermosetting resin having no softening point or a resin having a softening point of 200 ° C. or higher is preferable. Specifically, a thermosetting resin such as a polyimide resin can be used. In the present embodiment, a polyimide resin is preferable.

  The thickness of the heat resistant resin film 5 is preferably 1 to 700 μm, and by controlling within this range, the high purity silicon single crystal film 4 can be favorably and easily peeled off.

Step (4)
Next, by heating the high-purity silicon single crystal film 4 on which the heat-resistant resin film 5 is formed, the high-purity silicon single crystal film 4 together with the heat-resistant resin film 5 is used as a single crystal silicon wafer as a substrate. Peel from 1.

  The heating temperature is preferably 200 to 700 ° C, more preferably 300 to 500 ° C. Compared with a conventional ion implantation method or the like, it is possible to peel the high-purity silicon single crystal film 4 from the single crystal silicon wafer 1 as a substrate at a low temperature.

The heating temperature can be appropriately changed in relation to the shrinkage temperature and heat resistance temperature of the heat resistant resin film 5.
By heating to a predetermined heating temperature, the heat-resistant resin film 5 contracts and deforms, and mainly internal stress is applied to the halogen-containing silicon layer 3, so that the high-purity silicon single crystal film 4 together with the heat-resistant resin film 5 is applied. Is considered to be peeled off from the single crystal silicon wafer 1 as the substrate.

  Although the specific mechanism by which the high-purity silicon single crystal film 4 peels is not clear, the possibility of the following mechanism is conceivable.

  The halogen-containing silicon layer 3 contains a halogen atom, and the halogen atom is a defect of a silicon crystal in the halogen-containing silicon layer 3. For this reason, compared with the high-purity silicon single crystal film 4 or the single crystal silicon wafer 1, it is considered that the structure is brittle.

  The halogen-containing silicon layer 3 having a weak structure as compared with the surroundings tends to concentrate stress due to heating and becomes a fracture surface due to thermal shock, so that the high-purity silicon single crystal film 4 is a single crystal silicon wafer as a substrate. 1 is considered to be peeled off.

  Note that the above mechanism is merely an example of the possibility, and is not limited at all. For example, the fracture surface is not limited to the halogen-containing silicon layer 3, but the halogen-containing silicon layer 3 and the high-purity silicon single crystal film 4. Or an interface between the halogen-containing silicon layer 3 and the single crystal silicon wafer 1, a high-purity silicon single crystal film 4 or the like.

  Preferably, the silicon single crystal film 6 according to the present embodiment obtained in this way is mainly composed of a high-purity silicon single crystal film 4 and contains Si as a main component.

  Furthermore, in the silicon single crystal film 6 according to the present embodiment, a part of the halogen-containing silicon layer 3 may remain on one surface. The area and thickness of the remaining halogen-containing silicon layer 3 are not limited at all, and the halogen-containing silicon layer 3 may not remain.

  The silicon single crystal film 6 of the present invention thus obtained is self-supporting, excellent in flexibility, and improved in convenience of use, despite being thinned to a thickness of 50 μm or less. Can be achieved.

  In addition, the silicon single crystal film 6 of the present invention can be manufactured by increasing the size of the single crystal silicon wafer 1 serving as a substrate. Therefore, the silicon single crystal film 6 of the present invention can be used for a wide range of applications.

  In addition, the present invention is not limited to the above-described embodiment. For example, the appropriate peeling temperature differs depending on the type of the heat-resistant resin film 5, and it goes without saying that the temperature in each process varies depending on the specifications of the apparatus and the like. Furthermore, the thickness dimension of each part is only an example, and can be implemented with appropriate modifications within a range not departing from the gist of the present invention.

Example 1
A single crystal silicon wafer 1 (diameter: 2 inches) having a (1, 0, 0) surface with both surfaces mirror-finished was set on a sample holder (anode electrode) of a parallel plate type plasma CVD apparatus. The heater embedded in the holder was energized to heat the single crystal silicon wafer 1 to 350 ° C., and the plasma CVD apparatus was evacuated by a turbo molecular pump to 10 ⁻⁵ Pa.
<Process (0)>

First, in order to remove the oxide film 2 naturally formed on the surface of the single crystal silicon wafer 1, the hydrogen gas is supplied at a flow rate of 100 cc / min, the hydrogen gas is supplied into the plasma CVD apparatus, A high-frequency output of 100 W was supplied to the facing cathode electrode to generate hydrogen gas plasma. The natural oxide film 2 on the surface of the single crystal silicon wafer 1 was removed by plasma treatment for about 5 minutes. The presence or absence of the oxide film 2 was confirmed by in-situ observation with a spectroscopic ellipsometer attached to the apparatus.
<Step (1)>

Next, in order to form the halogen-containing silicon layer 3, the SiF ₄ gas flow rate was 5 cc / min, the hydrogen gas flow rate was 100 cc / min, and a high frequency output of 100 W was supplied to the cathode electrode for 30 minutes. At this time, the temperature of the single crystal silicon wafer 1 was set to 350 ° C. By this treatment, a halogen-containing silicon layer 3 having a thickness of 0.5 μm was formed on the surface of the single crystal silicon wafer 1.

Thereafter, the sample was taken out from the plasma CVD apparatus, and the halogen content of the halogen-containing silicon layer 3 was measured.
<Step (2)>

Next, in order to form the high-purity silicon single crystal film 4 on the halogen-containing silicon layer 3, SiH ₄ gas was supplied into the plasma CVD apparatus at a flow rate of 5 cc / min and hydrogen gas of 100 cc / min. The sample temperature was 350 ° C. Then, a high-frequency output of 100 W was supplied to the cathode electrode for 2 hours to form a 2 μm high-purity silicon single crystal film 4.

Thereafter, the sample was taken out from the plasma CVD apparatus, and the crystallinity of the high purity silicon single crystal film 4 was evaluated.
<Step (3)>

A thermosetting polyimide resin was applied to the surface of the sample on which the high-purity silicon single crystal film 4 was formed by spin coating so as to be 200 μm after drying. Thereafter, it was put in a dryer and heated to 280 ° C. to be cured.
<Process (4)>

Then, it set to the sample heating holder in a plasma CVD apparatus again, and it vacuumed to 10 ^<-1 > Pa and heated to 450 degreeC. When observing from the observation window attached to the apparatus, it was found that the film-like material was peeled off from the single crystal silicon wafer 1 substrate. When the heating was stopped and the sample was taken out from the sample holder, it was confirmed that the film-like substance was peeled off from the single crystal silicon wafer 1 cleanly.

  After confirming that the silicon single crystal film 6 to which the polyimide resin film 5 adhered was peeled from the single crystal silicon wafer 1, heating of the sample was stopped, the sample was cooled to room temperature, and taken out from the plasma CVD apparatus.

(Measurement method of halogen content of halogen-containing silicon layer 3)
The halogen content was measured by a secondary ion mass spectrometry (SIMS) method because of the feature that elements existing near the surface can be detected with high sensitivity. The measuring device used was IMS-4f manufactured by CAMECA. The acceleration voltage is 14.5 kv, a primary ion beam of cesium ions is irradiated to a region of 30 μmφ from an incident angle of 60 ° (in the sample normal direction), and measurement is performed on the surface of the halogen-containing silicon layer 3 of the sample. Went. The average value of the secondary ion intensity profile of the halogen in the depth direction obtained at this time was defined as the halogen content. The halogen content is obtained as a count (atom / cm ³ ).

Here, it is considered that the halogen-containing silicon layer 3 has a structure in which a part of Si atoms is replaced with a halogen element in a complete Si crystal. Therefore, from the value of the halogen atom count (atom / cm ³ ) by SIMS method, among the Si atoms (5 × 10 ²² atm / cm ³ ) that should exist per cm ³ in the case of a complete Si crystal, It can be determined how many Si atoms have been replaced by halogen atoms. This was defined as the halogen content of the halogen-containing silicon layer 3. The results are shown in Table 1.

(Evaluation method for crystallinity)
The crystallinity is evaluated using a spectroscopic ellipsometer (manufactured by HORIBA Jobin Yvon: UVISEL type), and the optical transition of 4.2 eV is the same as that of the single crystal silicon wafer 1 as the reference sample. It was confirmed against the surface of the high-purity silicon single crystal film 4 of the sample that the spectra had the same shape.

(Peelability evaluation method)
In the evaluation of peelability, it was confirmed by visual observation whether or not the surface of the silicon single crystal film 6 was peeled off without any cracks. The case where it was not peeled was rated as x, the case where it was peeled off but cracked, etc., Δ, the case where there was no crack as ○, and ○ as good. The results are shown in Table 1.

Table 1

  According to the manufacturing method of the present invention, it was confirmed that the silicon single crystal film 6 was easily and satisfactorily peeled from the single crystal silicon wafer.

  Of the obtained silicon single crystal film 6, the high purity silicon single crystal film 4 was confirmed to be single crystal silicon as a result of the evaluation of crystallinity.

  Moreover, although the obtained single crystal silicon film was a thin film with a film thickness of 2 μm, it was not visually cracked and was slightly glossy. Such a silicon single crystal film 6 of the present invention is excellent in surface smoothness and has a self-supporting property capable of maintaining its form even when laminated with a flexible resin film.

  As a result of SIMS analysis, since the halogen content of the halogen-containing silicon layer 3 was 1 atomic%, the halogen-containing silicon layer 3 was temporarily left on the surface of the obtained silicon single crystal film 6. Even in some cases, it can be said that the halogen content of the obtained single crystal silicon film 6 as a whole is 1 atomic% or less. Therefore, the silicon single crystal film 6 of the present invention contains 99 atomic% or more of Si atoms.

Examples 2-8
In Examples 2 to 8, samples were prepared under the same conditions as in Example 1 except that any of the conditions in steps (1) to (4) was changed as shown in Table 1. The results are shown in Table 1.

  As shown in Table 1, also in Examples 2 to 8, it was confirmed that the silicon single crystal film 6 was peeled off from the single crystal silicon wafer 1 easily and satisfactorily as in Example 1. The crystallinity of the obtained single crystal silicon film 6 was the same as in Example 1.

Example 9
In Example 9, a sample was manufactured under the same conditions as in Example 1 except that the step (0) was not performed (the oxide film formed naturally was not removed). The results are shown in Table 1.

  As shown in Table 1, it was confirmed that in Example 9 as well as Example 1, the silicon single crystal film 6 was easily and satisfactorily peeled from the single crystal silicon wafer 1. The obtained single crystal silicon film 6 had the same crystallinity as that of Example 1, but the surface was observed to be slightly distorted as compared with Examples 1 to 8 in which step (0) was performed. It was done.

Comparative Example 1
In Comparative Example 1, a sample was produced under the same conditions as in Example 1 except that the step (1) was not performed (the halogen-containing silicon layer 3 was not formed). The results are shown in Table 1.

  Since Comparative Example 1 does not have the halogen-containing silicon layer 3, even if it has the heat-resistant resin film 5, the silicon single crystal film 6 does not peel from the single crystal silicon wafer 1, and peeling failure became.

Comparative Example 2
In Comparative Example 2, a sample was produced under the same conditions as in Example 1 except that the step (3) was not performed (the heat resistant resin film 5 was not formed on the silicon single crystal film). The results are shown in Table 1.

  Since the comparative example 2 does not have the heat-resistant resin film 5, even if it has the halogen-containing silicon layer 3, the silicon single crystal film 6 does not peel from the single crystal silicon wafer 1, and the peeling failure occurs. became.

  That is, in the case where any one of the steps (1) to (4) according to the manufacturing method of the present invention is not provided (Comparative Examples 1 and 2), the thinned self-supporting silicon unit according to the present invention is used. It was confirmed that the crystal film 6 could not be obtained.

Comparative Example 3
In Comparative Example 3, a sample was produced under the same conditions as in Example 1 except that the heating temperature in the peeling step (4) was 20 ° C. The results are shown in Table 1.

  In Comparative Example 3, the heating temperature in the peeling step (4) was lower than the temperature suitable for peeling. Therefore, even if the halogen-containing silicon layer 3 is provided, the silicon single crystal film 6 is separated from the single crystal silicon wafer 1. Peeling did not occur, resulting in peeling failure.

Comparative Example 4
In Comparative Example 4, a sample was produced under the same conditions as in Example 1 except that the heating temperature in the peeling step (4) was 750 ° C. The results are shown in Table 1.

  In Comparative Example 4, since the heating temperature in the peeling process was higher than the temperature suitable for peeling, the silicon single crystal film 6 was peeled from the single crystal silicon wafer 1, but the polyimide resin was altered and the silicon single crystal film was 6 cracked. Therefore, the surface smoothness of the obtained silicon single crystal film 6 was inferior.

DESCRIPTION OF SYMBOLS 1 ... Single crystal silicon wafer 2 ... Oxide film 3 ... Halogen containing silicon layer 4 ... High purity silicon single crystal film 5 ... Heat-resistant resin film 6 ... Silicon single crystal film

Claims (5)

A step (1) of forming a halogen-containing silicon layer on the single crystal silicon wafer;
A step (2) of forming a high-purity silicon single crystal film having a desired thickness on the surface of the halogen-containing silicon layer;
Forming a heat-resistant resin film on the high-purity silicon single crystal film (3);
And a step (4) of peeling the high-purity silicon single crystal film together with the heat-resistant resin film with the halogen-containing silicon layer by heating. The method for producing a silicon single crystal film according to claim 1 , wherein the steps (1) and (2) are performed by an epitaxial growth method. The method for producing a silicon single crystal film according to claim 1 or 2 , wherein the steps (1) and (2) are performed by a plasma CVD method. The heat-resistant resin film, a method for manufacturing a silicon single crystal film according to claim 1 made of a polyimide resin. 5. The method for producing a silicon single crystal film according to claim 1 , wherein the heating temperature is 200 to 700 ° C. in the step (4).

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